On display it saids cats system fault. What is that?

have you got any fault codes out of the system? the normal cause of poor running and misfires are the on plug coils. the cat system will report a a misfire to the powertrain control module and that will flag a fault code for a cat problem. check the resistance of the spark plugs because if they are too low they can damage the coils and spike the powertrain control module.we used to change 6 plugs and coils for this very problem, very expensive. the lambda sensors are also troublesome, bank a easy, bank b, good luck. change the plugs and use jag recomended. the fault codes are the key to sorting it out

CHECK CATELIST CONVERTER

This is a generic warning message on Peugeot and Citroen cars.

It generally means that there is a fault within the emissions circuit. However it does not necessarily mean that there is a fault with the CAT or lambda sensors.

It could be one of many sensors or faults that causes the ECU to detect a fault and could led to this error message been displayed.
p3011 = fuel pump relay short to positive

But my advice is to clear the fault code. If it appears again then change the fuel filter and go from there. If the problem persist then as I said chec your emission circuit.

Hi:Just one code there, or your descripotion is about two or mode fault codes; we will need exactly what code number is detected there.

You could find code description here: obd_codes.html

Hope this helps

Hi there:Just one code there, or your descripotion is about two or mode fault codes; we will need exactly what code number is detected there.
You could find code description here: obd_codes.html
Hope this helps.

if its showing the electric zigzag thingy then most likely fault is the O2 sensor ,its flashing this fault as its getting too much fuel ,but it could also be a coil fault somewhere or ignition module as well as this will misfire and allow to unburnt fuel into cat throwing the light on ,also a fuel injector is staying open throwing too much unburnt fuel into cat

CATS System fault occure when oil is comming to combustion chamber and blow out into exhoust manifold becouse Valve seals is getting very old or oil rings is weak.

The only thing that will set this code is the catalytic converter or the oxygen sensor behind it. Way to tell if it is the sensor is to monitor voltage reading with scan tool and see if it is fluctuating the same as the upstream oxygen sensor. If it is the converter is "free flowing" and will have to be replaced. If the sensor is "flatlined" then it is most likely bad and setting the code.

its the O2 sensor for sure. normally, its good practice to change the sensor when changing out the muffler and cat system. doing it all together will prevent the sensor from faulting.

There are many reasons for a PO171 code, these need to be checked before replacing O2's:

Vehicle driven low on fuel or until it ran out of fuel

One or more injectors restricted or pressure regulator has failed

Fuel delivery system supplying too much or too little fuel during cruise or idle periods (e.g., faulty fuel pump, or dirty fuel filter)

Air leaks after the MAF sensor, or air leaks in the PCV system

Air leaks at the EGR gasket, or at the EGR valve diaphragm

Exhaust leaks before or near where the front HO2S is mounted

HO2S is contaminated, deteriorated or it has failed

Fuel control sensor is out of calibration (i.e., ECT, IAT or MAP)

Base engine "mechanical" fault affecting one or more cylinders.